Using warnings,
and paying attention to what they say,
is probably the single most effective way to improve the quality of your code.
This policy requires that the 'use warnings' statement must come before any other statements except package,
require,
and other use statements.
Thus,
all the code in the entire package will be affected.

If you make use of things like Moose::Exporter,
you can create your own modules that import the warnings pragma into the code that is useing them.
There is an option to add to the default set of pragmata and modules in your .perlcriticrc: equivalent_modules.